Research On Topology Of Single Input Expandable Switched Capacitor Multilevel Photovoltaic Inverter

Energy is an important lifeline closely related to mankind,and an important force for sustainable social development and stable economic growth.However,with the excessive dependence on traditional fossil energy,energy poverty is becoming increasingly serious,and renewable and clean energy such as solar energy,fuel cells,and wind energy have been vigorously developed and developed.When applied to fields such as solar cells and fuel cells,it is necessary for inverters to have a certain boost capacity to achieve better power conversion effects.The lack of boost capacity in traditional multilevel inverters makes the power conversion process extremely complex.In recent years,switched capacitor inverters have been proposed to achieve boost output.Firstly,the background and significance of the project were introduced,and the main characteristics and research significance of the current mainstream multi-level inverter topology were discussed.The development direction of switched capacitor inverters was elaborated,and the advantages and disadvantages of existing switched capacitor inverters were analyzed.Secondly,in response to the many drawbacks of traditional multi-level inverters,such as complex structures and excessive power device losses,this paper proposes an extended switched capacitor multi-level photovoltaic inverter topology.Firstly,the working principle of the nine level inverter topology is introduced;Designed the modulation scheme and calculated the device parameters;Simulate the topology accordingly;At the same time,it is compared with traditional multi-level inverters and recently proposed switch capacitor nine level inverters.After analysis,it is shown that the inverter proposed in this article has a simple structure,fewer total devices,lower cost,stronger boosting ability,lower total voltage stress,and the performance of capacitor voltage self balancing,reflecting the superiority of the topology.Then,on the basis of the nine levels,more levels of output can be expanded,using the first level expansion topology,namely the seventeen level inverter,as an example for explanation.An analysis of its working principle and the design of its driving logic have been conducted,demonstrating that using fewer devices in the 17 level topology can achieve stronger boost capability.Finally,the feasibility of this scheme was verified through simulation.The voltage feedforward and current quasi-proportional-resonant control are applied to analyze the grid connection of a nine level topology.The simulation results and theoretical analysis confirm each other,reflecting the excellent steady-state performance of the topology.Finally,a hardware experimental platform for the new switch capacitor nine level and seventeen level inverter systems was built,and control program design and experiments were conducted based on FPGA.The advantages of the nine level and seventeen level inverters were verified through experiments.